Bactericidal Activity of Psidiumguajava Leaves Against Some Pathogenic Microbes

This study was carried out to determine the antimicrobial activity of Psidiumguajava(PG) leavesextracts against some pathogenic microbes. The extracts of P.G leaves was fractionated and purified by preparative TLC technique, then subjected toGas Chromatography-Mass Spectroscopy (GC-MS) to identify the biologically active compounds.Thereafter, thetoxicity of the pure fractions was assessed in vivo using experimental rats. The P.G leaves were extracted with 80% ethanol,then the extracts were fractionated with nhexane, chloroform, ethyl acetate, n-butanol and water. The antimicrobial activities of the extracts and the fractions of P.G leaves were done on 3 clinical pathogenic strains namely, Staphylococcus (S)aureus, E. coli and Candida (C)albicans. The disc-diffusion and MIC & MBC tests were employed to evaluate the inhibitory effects of the extracts and the fractions. The result of this experiment showed that the ethanolic extract of P.G leaves had a significant (p< 0. 01) inhibitory effect on S. aureushowever the other strains were resistant. The nhexane fraction of P.G leaves showed a significant (p< 0.01) inhibitory effect on the two tested bacterial strains compared to other fractions. However, C. albicans resisted all the fractions. The zones of inhibition of the sensitive strains significantly (p< 0.05) increased when the concentrations of the ethanolic extracts and fractions were increased. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethanolic extracts of PG leaves were nearly equal. The PTLC of n-hexane fraction of P.G leaves showed 4 bands of different colors. These 4 bands were tested for antimicrobial activity and only band 1 gave highest antibacterial activity. Band 1 was further analyzed with GC-MS into variable biological compounds (n-hexadecanoic acid; 9-Octadecenoic acid;Octadecenoic acid; 9, 12Octadecenoic acid (Z,Z)-; Palmitoyl chloride; Hexadecanoic acid; Cyclotridecanone; Eicosanoic acid; Oleoyl chloride; N,N ' bis(trifluoroacetyl)-N,N'-ethylenebis(stearamide); Glycidol stearate; 1,2-Benzenedicarboxylic acid; 1Cyclohexyldimethylsilyloxybutane; 14-Beta-HPregna; Stigmasta-3,5-dien-7-one). The fractions were found nontoxic to rats. In conclusion, P.G leaves contain nontoxic active antibacterial compounds. Thus P.G leaves can be used as crude or in purified forms to treat patients suffering from intestinal infection caused by S.aureus andE. coli.